_Hirundo_, LINN. Syst. Nat. I, 10th ed. 1758, 191. (Type, _H.
rustica_, LINN.)
[Line drawing: _Hirundo horreorum._
1452]
Under the generic head of _Hirundo_ I propose to combine several
groups of American Swallows agreeing in moderate, depressed bill, with
straight commissure, and lateral nostrils overhung by membrane; the
tarsi feathered only at the upper end, or else entirely bare; the
lateral claws moderate, not extending beyond the base of the median;
the edge of the outer primary without hooks; the tail variable in
character, from a very deep fork to a slight emargination only.
Subgenera.
Tarsi slightly feathered on inner face at upper end; equal in
length to middle toe without claw.
Tail very deeply forked … _Hirundo_.
Tail slightly forked or emarginate … _Tachycineta_.
Tarsi entirely naked; lengthened equal to middle toe and half
its claw.